This invention relates to a shock absorber and more particularly to an improved shock absorber that permits better control of damping in both directions of operation.
The use of tubular-type shock absorbers for a wide variety of applications is well known. Such shock absorbers include a cylinder in which a piston is supported for reciprocation to define two fluid chambers. A piston rod is connected to the piston and extends through one of the chambers for connection to one of the two elements to be suspended. The cylinder is connected to the other of the two elements so that the volume of the two chambers vary as the elements move relative to each other. Normally, damping valves are provided within the assembly one of which permits controlled flow from the chamber in which the piston rod extends to the other chamber upon extension of the shock absorber. The other chamber is connected to a reservoir and a further valve means is provided in this connection for controlling the damping flow in the other direction.
A disadvantage with this type of construction is that when the device is undergoing a compression stroke, the actual volume of the fluid for use in the shock absorbing function that is displaced by the piston rod in the chamber through which it extends.
This type of shock absorber is frequently used in vehicle suspension systems and it is desirable to provide a relatively low damping force under low piston speeds so as to improve ride quality. However, vehicles are frequently driven over rough roads and particularly at high speeds and when this is the case then damping forces must be substantially increased.
However, with this type of device it is well known that the amount of fluid displaced normally in the contraction mode is only that displaced by the cross-sectional area of the piston rod in the chamber in which it passes. Thus, in order to obtain high damping forces, extremely small orifices must be required or the piston rod diameter substantially increase. However, both of these expedients then adversely affect the damping operation in the opposite direction.
It is, therefore, a principal object of this invention to provide an improved shock absorber that permits wide latitude in damping rates in both directions.
It is a further object of this invention to provide an improved tubular type of shock absorber that will offer greater latitude of damping control while still maintaining a compact size.
It is a further object of this invention to provide an improved shock absorber arrangement for vehicle suspension systems wherein damping can be effectively controlled in both directions with a compact and relatively simple construction.